diff --git a/src/main/java/org/cactoos/list/Immutable.java b/src/main/java/org/cactoos/list/Immutable.java
index 15220af0d..716e6f432 100644
--- a/src/main/java/org/cactoos/list/Immutable.java
+++ b/src/main/java/org/cactoos/list/Immutable.java
@@ -49,13 +49,13 @@ public final class Immutable<T> implements List<T> {
     /**
      * Encapsulated list.
      */
-    private final List<T> list;
+    private final List<? extends T> list;
 
     /**
      * Ctor.
      * @param src Source collection
      */
-    public Immutable(final List<T> src) {
+    public Immutable(final List<? extends T> src) {
         this.list = src;
     }
 
diff --git a/src/main/java/org/cactoos/list/ImmutableListIterator.java b/src/main/java/org/cactoos/list/ImmutableListIterator.java
index 000f5af28..508fb71b0 100644
--- a/src/main/java/org/cactoos/list/ImmutableListIterator.java
+++ b/src/main/java/org/cactoos/list/ImmutableListIterator.java
@@ -38,13 +38,13 @@ public final class ImmutableListIterator<T> implements ListIterator<T> {
     /**
      * Original list iterator.
      */
-    private final ListIterator<T> origin;
+    private final ListIterator<? extends T> origin;
 
     /**
      * Ctor.
      * @param iter Original list iterator.
      */
-    public ImmutableListIterator(final ListIterator<T> iter) {
+    public ImmutableListIterator(final ListIterator<? extends T> iter) {
         this.origin = iter;
     }